Warehouse clubs have become ubiquitous and Sam's Club and Costco are the two players that are by far the largest across the county. I've shopped at several Sam's Clubs here in Illinois and in other states and they've generally offered a similar experience with layouts and service varying between stores. Champaign doesn't have a choice so Sam's Club is the only game in town. The highlights of this location are that it is usually well stocked and clean. It seems a little smaller than some of the newer stores but I've never had a problem finding what I need.
However, the customer service leaves much to be desired. Staff often treats me as if they're doing me a favor rather than trying to earn my business. In particular, I had a bad experience with the auto shop purchasing some tires. Without going into all the details, the problem (including Sam's Club damaging new wheels through a careless installation) took over a month to fix and I ultimately had to take my vehicle to another tire shop to get all of the issues resolved. In the end I did get a credit from Sam's Club but given grudgingly as if I was cheating the store out of their hard earned money. The tire shop here is frequently overbooked and although you expect it to be busy in the holiday seasons, you should have your installation appointment honored if they give you the time. Tire staff is very unhelpful.
I limit my store purchases now to just the items I can't get elsewhere.